| With the development of green chemistry,cyclohexene hydration has attracted more and more attention because of its environmental friendliness and more economical characteristics than other processes.However,because the reaction system was a three-phase（liquid-liquid-solid）reaction system,where the catalyst was hydrophilic at the bottom of the water phase.Cyclohexene conversion was low since it was difficult to contact with the oil.Therefore,this paper improved the cyclohexene conversion by modifying HZSM-5 zeolite,and explored the energy barrier of cyclohexene hydration reaction by calculation to verify the feasibility of HZSM-5 modification,which could provide a basis for the industrialization.（1）OTS-HZSM-5 catalyst was prepared by alkylation modification of zeolite with n-octyltrimethoxysilane（n-octyltrimethoxysilane,OTS）;then subsequently characterized using XRD,FT-IR,NH3-TPD,Py-IR,SEM,BET,CA,TG and XPS.The results showed that the alkylation modification could increase the catalyst hydrophobicity without significantly reducing the acid site density.OTS-HZSM-5 catalyst showed better catalytic activity at alkylation loading=25%,reaction temperature=130 oC,water-ene molar ratio=5,reaction time=4 h,and catalyst dosage=1.65 g（10 wt%relative to water）.The cyclohexene conversion was 20.87%,and the cyclohexanol selectivity was close to 100%.（2）The HCl-HZSM-5 catalyst was prepared by acid modification of zeolite with hydrochloric acid;then subsequently characterized using XRD,FT-IR,NH3-TPD,Py-IR,SEM,BET,CA,TG and XPS,and the effect of acid modification on the structure of HZSM-5 catalyst was investigated.The results showed that acid modification could improve the catalyst hydrophobicity and increase the acid sites in the pores.The catalysts had better hydrothermal and configurational stability after acid modification.HCl-HZSM-5 catalyst showed better catalytic activity at reaction temperature=130 oC,water-ene molar ratio=6,reaction time=4 h,and catalyst dosage=1.65 g（10 wt%relative to water）.The cyclohexene conversion was 7.69%,and the cyclohexanol selectivity was close to 100%.（3）The HCl-OTS-HZSM-5 catalyst was prepared by acid and alkylation modification;then subsequently characterized using XRD,FT-IR,NH3-TPD,Py-IR,SEM,BET,CA,TG and XPS.Acid modification enabled HZSM-5 zeolite to remove some aluminum atoms,increasing specific surface area,pore volume,and acid sites.n-octyltrimethoxysilane（OTS）was grafted onto the HCl-HZSM-5 zeolite surface,i.e.,alkylation modification,to improve contact area between immiscible reactants.HCl-OTS-HZSM-5 catalyst showed better catalytic activity at reaction temperature=130 oC,water-ene molar ratio=6,reaction time=4 h,and catalyst dosage=1.65 g（10 wt%relative to water）.Consequently,cyclohexene conversion reached 24.07%and cyclohexanol selectivity was close to 100%.（4）Cyclohexene hydration was calculated using the 34T cluster model.The bridging hydroxyl and water molecule adsorption sites were explored,and the energy barrier of cyclohexene hydration reaction was calculated.Simulations confirmed that the reaction energy barrier for OTS-HZSM-5 catalyzed hydration reaction was=46.67 k J/mol,considerably less than for HZSM-5 zeolite（73.78 k J/mol）.The theoretical results reasonably explain the experiments and provide guidance to prepare catalysts with high catalytic activity. |
